Ch 20 Lymphatic System

Spleen, Thymus, Tonsils, Lymph nodes, Lymph vessels

List some organs that are part of the lymphatic and immune
system

Water, ions and other small molecules leak out of blood capillaries. If there was nothing to pick up the leaked out stuff, the tissues would swell. Lymphatic system to the rescue. The lymphatic capillaries pick up that stuff that leaks out and it becomes lymph. It is returned to the circulation at the subclavian veins.

Where does lymph fluid come from?

The fluid part of blood, also known as PLASMA

What other body fluid is lymph similar to?

Water

Lymph is mostly made of _____

1. They are blind ended

2. They have flap-like mini valves that let things enter, but won’t let anything leave

List two ways lymphatic capillaries are different to blood capillaries

back towards

Lymphatic vessels are trying to move the lymph back towards/away from (pick one) the heart.

Trunks & dunks

Lymph is collected in large vessels called

Thoracic duct

Lymph coming back from the legs, abdomen, left arm and left
head dumps into the

Right lymphatic duct

Lymph coming back from the legs, abdomen, left arm and left
head dumps into the

Subclavian veins

Which large blood vessels does lymph dump into?

Veins

Large lymphatic vessels have valves and thin layers of smooth
muscle. They are most similar to

The same ways blood is pushed through veins. The skeletal muscle contracts when your body moves and squashes the tube, pushing the lymph forward.

If there is no pump, how is lymph pushed through the vessels?

• B-lymphocytes: make antibodies

• T-lymphocytes: attack cells infected by pathogens

• Macrophages: phagocytes that eat + destroy pathogens

• Dendritic cells: special phagocytes only found in skin which eat pathogens

• Reticular cells: these make reticular fibers, an important scaffold in lymph organs like the spleen to hold things together

List the function of these cells:

• B-lymphocytes

• T-lymphocytes

• Macrophages

• Dendritic cells

• Reticular cells

B lymphocytes

Which type of lymphocytes form follicles

The B lymphocytes are copying by cell cycle and mitosis

What is going on in the germinal center of a follicle?

Check and clean lymph

What is the function of a lymph node?

Approach, A for approach

Lymph comes into the lymph node on the ___________
lymphatic vessel

Efferent, E for exit

Lymph leaves the lymph node on the ___________ lymphatic
vessel

The white blood cells are using the lymph node as a place to copy. An increase number of cells, swells the node

Why do lymph nodes swell when you have an infection?

Remove dead, damaged and non-functioning RBC. It is the RBC graveyard

What is the major function of the spleen?

Arteries

Is white pulp around arteries or veins?

On the heart

Where is the thymus located?

It is the place where T lymphocytes mature, i.e. the place they go through positive and negative selection

What is the major function of the thymus?

NO, T only

Are B-lymphocytes ever found in the thymus?

On every opening of the body. In the mouth, nose, vagina, anus, urethra and in your intestine where food crosses from digestive system to blood.

• Basically anywhere something is coming IN to the body

Where is MALT found?

It picks up the fluid that build up in the capillary

How does the lymphatic system prevent edema?

Fat and fat soluble vitamins (A, D, E, K) from the GI tract to the blood

What vitamins are transported in the lymph?

Immune system

What other system is the lymphatic system closely linked to?

• (not an organ) Lymphatic vessels

• Lymphatic tissue

• Lymphatic nodules

• Lymph nodes

• Tonsils

• Spleen

• Thymus

Name the organs of the lymphatic system (6 + 1 non organ)

Slide 3

Be able to label the key organs on a picture

Remember how blood is filtered out of capillaries into interstitial fluid, lymph is that same fluid which gets picked up by the lymphatic capillaries

Where does lymph come from?

Water

What is lymph mostly made of?

Ions, nutrients, gases, some proteins, Hormones, enzymes, waste products

What kinds of substances would you find in lymph?

Plasma

What other body fluid does lymph closely resemble?

Bones, teeth, nervous system, bone marrow

Where would lymph capillaries NOT be found?

because brain has blood brain barriers which prevents fluid leaving capillaries. If there is no capillary filtration, there is no lymph there to pick up

Why does it make sense that the brain has no lymph capillaries?

Lacteals

What are the special lymphatic capillaries of the digestive system called?

Epithelial

Lymph capillaries are made of 1 layer of _______ cells (hint-same
cells that blood capillaries are made of).

there is no vessel which carries lymph in. there are blind ended capillaries

What vessel carries lymph into lymph capillaries?

Yes

Do the mini-valves allow fluid to enter the lymph capillary?

No, only enter

Do the mini-valves allow fluid to exit the lymph capillary?

valves

What structure also found in veins are found in lymphatic vessels to ensure one way flow of lymph?

Towards

Is lymph flowing back toward the heart or away from the heart?

drains right side of head, right-upper limb, right thorax

What part(s) of the body does the right lymphatic duct drain?

Drains lymph from entire body below diaphragm and drains left thorax, left arm and left head and neck

What part(s) of the body does the thoracic duct drain?

cisterna chyli

What is the bulge around L2 on the thoracic duct called?

right subclavian vein

Where does the right lymphatic duct drop lymph back into the cardiovascular
system?

left subclavian vein

Where does the thoracic duct drop lymph back into the cardiovascular system?

Lymphatic node

What are the bumps (bulges) seen along the lymphatic vessels called?

Slowly

Does lymph flow slowly or very fast?

Fight antigens directly + regulate the immune response

What is the function of T-lymphoctyes?

Produce antibody secreting plasma cells

What is the function of B-lymphoctyes?

Red Bone Marrow

Where are B and T lymphocytes made?

Phagocytes, eat + destroy pathogen

What is the function of macrophages?

Monocyte

What are macrophages called when they are inside blood vessels?

Skin

Where would you find dendritic cells?

Search pathogens, eat + destroy any pathogens

What is their function dendritic cell?

Reticular fibers/ CT

What type of tissue is made by reticular cells?

Thymus

Every lymph organ except the ______ has reticular tissue inside

Only B-lymphoctyes form follicles. Follicles are organized in a circular shape and usually have a capsule. Diffuse tissue is not organized, the cells are never in a capsule

What marks the difference between diffuse and follicular tissue?

B-lymphocytes

What type of lymphocytes form follicles?

Lymphocytes are proliferating (copying)

What is happening in the germ center of a follicle?

(Lighter staining center)

Lymph filter cleans debris and is examined by the immune system. Also notice the presence of pathogens (activate immune system)

What is the function of lymph nodes?

Yes

Are lymph nodes encapsulated?

Dense fibrous CT

What is the capsule made of?

Connective tissue strands which separate lymph node into sections

What are trabeculae

Cortex

What is the outer part of the lymph node called?

Inner medulla

What is the middle of the lymph node called?

Both B and T-lymphocytes

• B cells will be organized into follicles

• T cells will be in the medullary chords

Which immune cells are found inside lymph nodes?

B- lymphoctyes form follicles so wherever there is a follicle

How do you know which area of the lymph node has B-lymphocytes?

B cells are dividing making copies of themselves

What is happening in the germ center of a lymphoid follicle?

Afferent lymphatic vessels

Which vessel brings lymph INTO a lymph node?

Efferent lymphatic vessels

Which vessel carries lymph OUT OF a lymph node?

because WBC copy when there is an infection and More cells will increase the size of the node and stimulate pain receptors

Why do lymph nodes swell when they are infected?

Cancer cells are also trapped in lymph nodes, we can use this to determine how far a cancer has spread

How can lymph nodes be used to track the spread of cancer?

Located on left side below diaphragm, lateral to stomach

Where is the spleen located?

Yes the spleen is surrounded by fibrous capsule

Does the spleen have a capsule?

Splenic artery

Which artery brings blood to the spleen?

Splenic vein

Which vein collects blood from the spleen?

Hilum

What is the indentation called where the blood vessels enter and leave?

• In the spleen, the blood is checked and any dead or damaged red blood cells are removed

• Debris and foreign matter is removed from blood

Why is the spleen important in the life of RBC?

Iron, amino acids, Extra monocytes and platelets

Name some things that are stored in the spleen

Splenectomy

What is it called when you have your spleen removed?

Liver + bone marrow

Which organs take over the functions if your spleen is gone?

White pulp

Clusters of lymphocytes around arteries are called

Red pulp

Clusters of macrophages around venous sinuses are called

Heart

Which organ is the thymus superior to/on top of?

2 lobes

How many lobes does the thymus have?

Begins to atrophy (shrink)

What happens to the thymus as you get older?

T

The thymus is really important for _____ lymphocytes

What happens to T-lymphocytes at the thymus?